diff --git a/src/kits/tracker/ContainerWindow.cpp b/src/kits/tracker/ContainerWindow.cpp
index 2888ca0c10..19001a3d68 100644
--- a/src/kits/tracker/ContainerWindow.cpp
+++ b/src/kits/tracker/ContainerWindow.cpp
@@ -3272,6 +3272,8 @@ BMenu*
 BContainerWindow::AddMimeMenu(const BMimeType& mimeType, bool isSuperType,
 	BMenu* menu, int32 start)
 {
+	AutoLock<BLooper> _(menu->Looper());
+
 	if (!mimeType.IsValid())
 		return NULL;